The present invention relates generally to the field of printing. In particular, a method and apparatus for printing upon diverse media including standard graphics arts coated ink jet print media materials, but especially fibrous and woven materials (e.g., textiles) with a specially adapted wide format in drop-on-demand ink jet print engine.
The present invention addresses issues presented in adapting thermal drop-ondemand ink jet printing techniques for applying colorant to printing media that fails to trap all the ink emitted onto the surface of the printing media (this includes perforated print media materials, blown fiber materials, and textile materials, to name just a few).
In the prior art related to textile printing typically vast amounts of ink are rapidly applied to rapidly moving fiber substrates (temporarily adhered to a moving belt) via a set of rotary screens each having a desired pattern associated therewith. The colors of the ink are known as xe2x80x9cspotxe2x80x9d color inks and they do not typically interact with other colors to form intermediate colored prints. By adding different colors and/or patterns the textiles eventually are rendered in a final design. The textile material is then typically exposed to heat and/or water vapor or other catalyst to fix the ink to the textile fibers. In the case of reactive inks the textile fibers actually chemically bond to the ink molecules during this step so that the final printed product is permanently marked and may be thereafter repeatedly washed without significant degradation of the printed product.
In ink jet printing a print head operated under precise electronic control typically opposes a portion of printing media so that an image may be printed thereon. The present invention addresses ink jet printing upon textiles.
In a traditional ink jet printing a roll of media attaches to a rotating supply spool and then passes under one or more discrete ink emitting print elements (xe2x80x9cnozzlesxe2x80x9d) in a printing zone which is essentially a platen secured so that a carriage articulated in the axial direction reciprocates thereacross. The printing media is rigidly coupled to a substantially planar surface and the nozzles are articulated to cover the media over the width of the media. In a reciprocating carriage-base print engine the media is incrementally stepped over a platen surface in one direction while the nozzles reciprocate across the media in a direction orthogonal to direction the media advances.
Thus, a need exists in the art of digital ink jet printing to advance the state of the art for emitting ink droplets in order to improve the quality and the visual clarity of text, graphics, and color appearing on textile media. Further, a need exists in the prior art to solve issues related to the performance limitations of known non-specialized print engines which emit ink from nozzles onto a printing media. Finally, a need exists in the art to improve the yield of quality digital output given mechanical constraints imposed by use of ink emitting print heads mounted at some distance above a printing media so that ink droplets reach a location on the printing media as close as possible to the preselected location associated with the primary droplet and are dried prior to being wrapped upon a take-up spool.
The method and apparatus of the present invention increases the precision for controlling diverse printing substrates during printing operation while ink is emitted from an ink jet print head to form patterns upon the printing media substrate. The present invention addresses several long-standing obstacles to high quality printed output upon many nontraditional print media, including media handling for nonbacked, unsupported, fibrous print media. The print media traverses the engine in a complex pathway in the preferred embodiment; including, continually advancing from a powered media supply roll through a cross-web tensioning area, an idler pulley, then over a full-web media advance grit roller, through a unique xe2x80x9copen webxe2x80x9d printing zonexe2x80x94where the media is briefly suspended during application of ink, over an idler pulley, through a forced heating zone (preferably dual-sided), and then over another idler pulley, and finally onto a take-up spool which is biased against the force created by the powered media supply spool.
The engine of the present invention utilizes this open-web printing zone, dual forced air heating of both sides of freshly printed media, and a continuously biased tension in the axial web directions and cross-web directions for maximum effect on fibrous media in particular, although the system lends itself to use in ink jet graphics arts applications. The media is preferably loaded in a center-justified orientation and the engine is tolerant of traditionally produced textile media rolls, cores, and fabric varieties.
A removeable pad may optionally be disposed on top of a platen frame member and under the print media pathway so that any ink that penetrates a porous media in the open web print zone impinges upon the pad where it can be collected and disposed of properly. If placed proximate to the printing media pathway, the removeable pad furthermore reduces the amplitude of any media wrinkles and thereby reduces drop placement errors which might cause visual artifacts.
After printing, the textile media typically requires post treatment, such as a process of steaming the textile and/or washing the printed textile in a solution of soap and water to remove excess colorant.
A preferred technique of operating the powered supply spool and the biased take-up spool is disclosed in U.S. Pat. No. 5,751,303 issued to Erickson et al. and entitled, xe2x80x9cPrinting Medium Management Apparatus,xe2x80x9d the entire contents of which is incorporated herein by reference. Briefly, this patent reference teaches use of opposing low torque motors driving the supply and take-up spools of an ink jet print engine so that a consistent web tension is maintained during printing operations. In the context of the present invention, this technique proves extremely useful because particularly when printing upon diverse un-backed textile media inherently creates problems with a stable web tension so that the media does not snag on one or more portions of the media handling mechanism(s) when energized.
The present invention furthermore preferably utilizes salvage edge maintenance members that provide a couple of features and benefits to the process of ink jet printing upon textile substrates. First, the edges of many print media, particularly textile materials, are often irregular and have a tendency to curl thereby creating a tendency for the extremely sensitive orifice plates of thermal ink jet cartridges to impinge thereon, thus potentially damaging the cartridges and likely ruining at least that particular section of printing substrate with undesirable ink droplets and smearing of ink from the orifice plates.
A print engine built along the lines suggested and taught herein will preferably handle at least sixty-three inch (63xe2x80x3) width print media (although scaling the present invention beyond this width is reasonably foreseeable), has a center-justified loading and printing configuration, and an xe2x80x9cauto-lockingxe2x80x9d nip roller assembly proximate the full-web grit roller member for ease of media loading. Furthermore, such a print engine preferably handles three inch (3xe2x80x3) diameter supply spools (xe2x80x9ccoresxe2x80x9d) presently commonly utilized in the textile printing industry and should support media having irregular edges as well as partial interior cores made of cardboard or similar material. Also, such a print engine preferably utilizes many print heads, with twelve (12) to sixteen (16) discrete disposable thermal ink jet print cartridges operating in concert to rapidly and accurately print myriad colors, patterns and text upon diverse textile media material(s).